Federal drug regulators are receiving an increasing amount of blood cancer reports from users of some drugs designed to treat inflammatory bowel disease (IBD).
The FDA issued a drug safety alert on April 14 for tumor necrosis factor (TNF) blockers, including Cimzia, Enbrel, Humira, Remicade and Simponi, as well as other types of drugs like azathioprine and mercaptopurine. The agency says a number of reports have linked the drugs to a rare cancer of white blood cells in children and young adults known as Hepatosplenic T-Cell Lymphoma (HSTCL).
The FDA has received 43 reports of HSTCL by patients who used TNF blockers, azathioprine or mercaptopurine, and the agency indicated that most of the cases involved patients treated with a combination of drugs that were known to suppress the immune system. However, the FDA also received reports of HSTCL from patients who were on azathioprine or mercaptopurine alone.
The drug most frequently connected to cases of HSTCL was Remicade, which was mentioned in 20 reports, but 18 of those patients were on either mercaptopurine or azathioprine as well. Azathioprine was the second most common drug mentioned in the reports. It was taken by 12 patients who were diagnosed with HSTCL.
Most of the cases involved patients being treated for ulcerative colitis and Crohn’s disease, both of which are forms of IBD. However there were at least two reports of patients who reported HSTCL after being treated for rheumatoid arthritis and one patient who was being treated for psoriasis.
HSTCL is a deadly cancer that affects the white blood cells and is highly aggressive; spreading quickly. The FDA urged health care professionals to carefully weigh the benefits of these drugs with their side effects.
Label warnings have already been updated for Remicade and Humira, and updates are in the process to warn consumers about the possible HSTCL side effects of azathioprine and mercaptopurine as well.
In 2009 the FDA required black box warnings be placed on all TNF blockers warning of the increased risk of childhood cancer. The FDA found that incidents of cancer began to appear about 30 months after TNF blocker treatment in some children being treated for juvenile rheumatoid arthritis, psoriatic arthritis, plaque psoriasis, ankylosing spondylitis, inflammatory bowel disorder and Crohn’s disease.
According to the FDA’s Adverse Event Reporting System, between 1998 and 2008, approximately 30 children using Remicade, Enbrel and Humira reportedly developed cancer. About half of the cancers were lymphomas, including both Hodgkin’s and non-Hodgkin’s lymphoma. The other cancers included leukemia, melanoma and solid organ cancers. Some of those cases have been fatal.